I recently purchased 2 Soundcraft 32-4-2 200B Consoles complete with power supplies and road cases. I was ready to start the ground mod, when I noticed that the PCB traces on the channel board was scratched out in the vicinity of the 20 pin ribbon cable. There are also 2 jumpers that have been soldered onto the bottom of the board. All of the 64 channel strips between these 2 boards have been modified in this way.

My question is whether or not anyone can shed some light on why this was done and what are the benefits if any. The channel strips are all the parametric hi mid and lo mid type.